1. Field of the Invention
The present invention relates generally to alternating signal pattern recognition systems and, more particularly but not by way of limitation, it relates to an improved signal processing system for comparison of non-linearly, related geosignals to extract maximum information therefrom.
2. Description of the Prior Art
Recent developments in the seismic prospecting technology have seen extensive development of techniques and computer processes for integrated processing of compressional wave data, shear wave data and/or mode converted data in order to derive additional parameter data therefrom. For example, it has been a primary quest to process seismic shear wave data and compressional wave data for the same terrain, albeit that energy velocities differ, in order to solve for V.sub.s /V.sub.p ratios which have a direct relationship with Poisson's ratio and other earth properties. Seismic shear wave data can provide an added dimension to compressional wave data to enable better, more accurate prediction of the properties of an earth cross-section and identification of the lithologies. Of particular interest is the publication of S. N. Domenico, "Rock Lithology and Porosity Determination From Shear and Compressional Wave Velocity", Geophysics, Vol. 49, 1984, pp 1188-1195. This paper discusses fully the usefulness of V.sub.s /V.sub.p ratios and shear wave velocities for the identification of lithologies.
An estimate of the V.sub.s /V.sub.p ratios is obtained when corresponding events in both the compressional and shear wave can be matched. This requires a time equalization of the counterpart waves as discussed by P. Anno, "Static Solutions and Event Correlations--Two Critical Aspects of Shear Wave Exploration", PROC. 53rd Annual SEG Meeting, 1983, p 347-349.
Yet another disclosure of interest is that of McCormack, Dunbar and Sharp, "A Case Study of Stratigraphic Interpretation Using Shear and Compressional Seismic Data", Geophysics, Vol. 49, 1984, pp 509-520, which teaches the matching of events for either or both of shear and compressional seismic sections using area well data to generate synthetic traces for comparison with the seismic traces. Finally, the patent art is best exemplified by U.S. Pat. No. 4,422,165 in the name of Thomas et al entitled "Maximum Likelihood Estimation of the Ratio of the Velocities of Compressional and Shear Waves". This teaching is directed to derivation of V.sub.s /V.sub.p data by linearly time equalizing shear and compressional wave data for subsequent maximum likelihood estimation. Thomas et al teach a computer-aided process for linear signal matching as directly correlated comparisons are made.